Jampacked release calendars and executive intrigue make for an especially stressful blockbuster season as the $200 million gambles begin rolling out.

With U.S. ticket sales already down 11 percent this year and the number of big-budget movies sharply up, summer 2013 is turning into a nail-biter for Hollywood. Volatile political situations at several studios are making matters worse for top executives. The Hollywood Reporter breaks down the major risks for each studio and the executives who will be sweating in their corner offices.

SONY

Sony Pictures' parent has denied that the division is for sale, but activist shareholder Daniel Loeb now is pushing the company to spin off its entertainment assets. Amid the pressure on studio chiefs Michael Lynton and Amy Pascal, Sony will release seven big films this summer, tops in Hollywood. After Earth, a sci-fi epic from M. Night Shyamalan starring Will Smith and son Jaden, enters a crowded market May 31. Competitors believe it might have trouble matching the $37.1 million domestic bow of April’s similarly apocalyptic Oblivion, which featured Tom Cruise. But no one should underestimate Smith’s star power. His Men in Black 3 grossed $624 million worldwide for Sony last summer, though it cost too much (in fact, a blistering New York Timespiece May 18 pegged Sony’s overall profit margin at a slim 6.5 percent).

Other risks include White House Down, which follows the similarly themed Olympus Has Fallen ($132.5 million in March). Still, it's director Roland Emmerich in his wheelhouse (his last outing, 2012, grossed $769 million worldwide), and it stars Channing Tatum and Jamie Foxx. On July 12 comes Grown-Ups 2, a follow-up to a comedy that grossed $271.4 million in 2010 but now must compete with mega-budgeted Pacific Rim from Warner Bros. July also brings The Smurfs 2 (one of many animated films in the game this summer, but the last one was a sleeper hit that grossed $563 million worldwide). A big question mark is Matt Damon’s Elysium, another sci-fi bet in August, from District 9 filmmaker Neill Blomkamp.

Film chief Jeff Robinov needs to preside over a strong summer to quell speculation about his future following the elevation of Kevin Tsujihara to the top job. Having stumbled at the beginning of the year with Gangster Squad and Jack the Giant Slayer, he must have been relieved when the risky Great Gatsby performed. The Hangover Part III probably is critic-proof but faces a strong Memorial Day rival in Universal’s Fast & Furious 6, pursuing the same young male audience. And the movie could be harmed if word-of-mouth is not good. “The second, third and fourth weekend could turn out to be what matters,” says Warners distribution chief Dan Fellman.

Buzz is good on the studio’s biggest bet of the summer, Man of Steel (June 14), which should successfully reboot the Superman franchise. Riskier is Guillermo del Toro’s robots vs. monsters epic Pacific Rim in July, but Warners only has a 25 percent stake in the film. Its main financier, Legendary Pictures, is the bigger question. Founder Thomas Tull has made no secret that he is looking for a new home, possibly Universal, and if his company takes a hit, his mood isn’t likely to improve.

Warners also is high on the July 19 horror film The Conjuring from its New Line division, which would be a boost to New Line leader Toby Emmerich after the underperforming Jack and The Incredible Burt Wonderstone earlier this year.

PARAMOUNT

J.J. Abrams’ Star Trek Into Darkness is underwhelming domestically ($83.7 million and counting) but performing far better overseas, which was one of Paramount’s objectives with the second installment of the rebooted franchise. The big remaining question mark is the troubled Brad Pitt zombie film, World War Z, which opens only one week after Man of Steel, on June 21. The studio financed extensive reshoots -- or, rather, shoots, since the third act was entirely reconceived -- and executives have been in overdrive trying to reverse negative buzz.

Paramount had an arid summer last year, but its known for managing its numbers well, and that keeps Viacom president and CEO Philippe Dauman happy, so it might not matter whether the studio has pulled WWZ out of the fire.

Fast & Furious 6 looks poised to deliver. (But can it match Fast Five’s $626.1 million in such a crowded market?) Chiefs Adam Fogelson and Donna Langley have turned in an improved performance in recent months, with such hits as the horror movie Mama and the comedy Identity Thief. Despicable Me 2 (July 3) seems like a sure thing despite the abundance of animated fare this summer. But RIPD, a supernatural action movie with Ryan Reynolds, has some joking that it should drop the “D” from the title. Sources say bosses at Comcast expect this film to lead to a loss.

While the parent seemed to be shopping openly for new management for the studio in the past year, perhaps that moment has passed. Things are going better, and NBCUni CEO Steve Burke may be too absorbed in issues with NBC to turn his attention to the movie business, which is alien turf to him.

DISNEY

What exactly is the budget of The Lone Ranger? Disney chairman Robert Iger personally intervened to lower the cost of the Johnny Depp Western from $250 million to $215 million. Now that original figure is believed to be a distant memory as the Gore Verbinski-directed film heads for a July 3 release up against Despicable Me 2, which could siphon off families.

But Disney is raking in Iron Man 3 money ($1 billion and counting worldwide), and Ranger was greenlighted before Disney chief Alan Horn took the job. The good news is that a new trailer looks fun, prompting a veteran producer with no ties to the studio or the project to declare: “The Disney marketing turbine is very powerful, so my bet is that it's a hit.”

Disney also has Pixar’s Monsters University on June 21, and while the footage shown at Cinemacon didn't wow theater owners, the Pixar brand is as safe a bet as they come.

FOX

Sandra Bullock and Melissa McCarthy’s cop comedy The Heat, directed by Paul Feig (Bridesmaids), could be something for the hungry female audience, and ladies will probably go with the guys to see Hugh Jackman reprise a signature role in The Wolverine in July.

But first, Fox’s animated Epic also could open north of $40 million over Memorial Day weekend, and it has the kid market to itself until June 21. Then all hell breaks loose. “It used to be two animated films a summer. Then there were three or four. This summer, there are six. It’s too many,” says one exec. Fox also will release Turbo, the latest from DreamWorks Animation, in July.

These are films that were put into the pipeline when studio chief Jim Gianopulos was still teamed with the now-departed Tom Rothman. The assumption is that Gianopulos will either add or be paired with another hands-on creative executive before another summer rolls around.